index.js

var EventEmitter = require("events").EventEmitter,
	util = require("util");

//Load C++ binding
var binding = require("./build/Release/HID.node");

//This class is a wrapper for `binding.HID` class
function HID() {
	//Inherit from EventEmitter
	EventEmitter.call(this);

	/* We also want to inherit from `binding.HID`, but unfortunately,
		it's not so easy for native Objects. For example, the
		following won't work since `new` keyword isn't used:

		`binding.HID.apply(this, arguments);`

		So... we do this craziness instead...
	*/
	var thisPlusArgs = new Array(arguments.length + 1);
	thisPlusArgs[0] = null;
	for(var i = 0; i < arguments.length; i++)
		thisPlusArgs[i + 1] = arguments[i];
	this._raw = new (Function.prototype.bind.apply(binding.HID,
		thisPlusArgs) )();
	
	/* Now we have `this._raw` Object from which we need to
		inherit.  So, one solution is to simply copy all
		prototype methods over to `this` and binding them to
		`this._raw`
	*/
	for(var i in binding.HID.prototype)
		if(i != "close")
			this[i] = binding.HID.prototype[i].bind(this._raw);

	/* We are now done inheriting from `binding.HID` and EventEmitter.

		Now upon adding a new listener for "data" events, we start
		polling the HID device using `read(...)`
		See `resume()` for more details. */
	this._paused = true;
	var self = this;
	self.on("newListener", function(eventName, listener) {
		if(eventName == "data")
			process.nextTick(self.resume.bind(self) );
	});
}
//Inherit prototype methods
util.inherits(HID, EventEmitter);
//Don't inherit from `binding.HID`; that's done above already!

HID.prototype.close = function close() {
	this._closing = true;
	this._raw.close();
};
//Pauses the reader, which stops "data" events from being emitted
HID.prototype.pause = function pause() {
	this._paused = true;
};
HID.prototype.resume = function pause() {
	var self = this;
	if(self._paused && self.listeners("data").length > 0)
	{
		//Start polling & reading loop
		self._paused = false;
		self.read(function readFunc(err, data) {
			if(err)
			{
				//Emit error and pause reading
				self._paused = true;
				if(!self._closing)
					self.emit("error", err);
				//else ignore any errors if I'm closing the device
			}
			else
			{
				//If there are no "data" listeners, we pause
				if(self.listeners("data").length <= 0)
					self._paused = true;
				//Keep reading if we aren't paused
				if(!self._paused)
					self.read(readFunc);
				//Now emit the event
				self.emit("data", data);
			}
		});
	}
};

//Expose API
exports.HID = HID;
exports.devices = binding.devices;